Identification of G protein-coupled receptors potently stimulating migration of human transitional-cell carcinoma cells.
The expression of G protein-coupled receptors inducing calcium mobilization and stimulating cell migration was examined in human transitional-cell carcinoma (J82) cells. Measurements of cytoplasmic Ca2+ concentration ([Ca2+]i) and phospholipase C activity indicated that these cells express several calcium-mobilizing receptors, including those for lysophosphatidic acid (LPA), thrombin, bradykinin, bombesin and histamine, of which only the LPA response was sensitive (approximately 50%) to pertussis toxin (PTX). Migration of J82 cells was strongly stimulated by LPA and thrombin, by 5- to 20-fold, whereas bradykinin, bombesin and histamine were ineffective. Migration induced by either LPA or thrombin was inhibited by the actin cytoskeleton-disrupting agent, cytochalasin B, by the Rho protein-inactivating Clostridium difficile toxin B, by preventing [Ca2+]i transients with an intracellular calcium-chelating agent, and by the phorbol ester, phorbol 12-myristate 13-acetate, which also blocked the LPA- and thrombin-induced [Ca2+]i increases. On the other hand, ADP-ribosylation of Gi type G proteins by PTX abrogated the migratory response to LPA, without affecting the thrombin effect. Similarly, raising cAMP levels inhibited, by about 50%, the LPA- but not the thrombin-induced J82 cell migration. In conclusion, human transitional-cell carcinoma (J82) cells express various G protein-coupled, calcium-mobilizing receptors, out of which only those for LPA and thrombin stimulate cell migration, indicating that phospholipase C-derived second messengers per se are not sufficient for initiating this response. The complex signal transduction processes leading to LPA- and thrombin-stimulated motility of these human carcinoma cells apparently involve several common, essential factors, such as [Ca2+]i changes and Rho protein-regulated reorganization of the cytoskeleton, as well as some distinct components, most notably distinct subtypes of heterotrimeric G proteins and apparently also distinct cAMP-sensitive targets.
Lümmen
G
G
Institut für Pharmakologie, Universitätsklinikum Essen, Germany.
Virchow
S
S
Rümenapp
U
U
Schmidt
M
M
Wieland
T
T
Otto
T
T
Rübben
H
H
Jakobs
K H
KH
D002118:Calcium / Q000378:metabolism*; D002295:Carcinoma, Transitional Cell; D002465:Cell Movement / Q000502:physiology*; D019204:GTP-Binding Proteins / Q000032:analysis* / Q000502:physiology; D006801:Humans; D007295:Inositol Phosphates / Q000096:biosynthesis; D010712:Phosphatidic Acids / Q000494:pharmacology; D011956:Receptors, Cell Surface / Q000032:analysis*; D043562:Receptors, G-Protein-Coupled; D049368:Receptors, Lysophosphatidic Acid; D018179:Receptors, Thrombin / Q000032:analysis*; D013917:Thrombin / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000187:drug effects; D001749:Urinary Bladder Neoplasms
D007295:Inositol Phosphates; D010712:Phosphatidic Acids; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D049368:Receptors, Lysophosphatidic Acid; D018179:Receptors, Thrombin; D013917:Thrombin; D019204:GTP-Binding Proteins; D002118:Calcium